A company’s ability to change increasingly depends on the ability to change its IT, something referred to as «IT agility» here. High IT agility can contribute to increased business agility and thus create a competitive advantage. In this paper we look at which factors influence IT agility and how the IT agility can be increased. The main body of the paper, however, is devoted to the research question how IT agility can be measured and actively managed. Here, the focus is on the IT application systems landscape, a resource of significant importance for the IT agility and competitiveness of a company.